I currently have three vendors for my store at http://www.greenandchic.com and several others I am considering adding on when my site takes off. All of the vendors gave me the wholesale price and the suggested (most of the time, required) retail price which is usually very close to 50% give or take. So if I am selling a body wash for $18, I paid $9 for it. Some vendors have strick requirements because they dont want to see their products discounded on other places like Ebay.
I would ask them if they already set up suggested retail prices for their sellers and take it from there.